Networks interconnecting end stations increasingly use asynchronous transfer mode (ATM) schemes for transmission of information. In an ATM network, transmitting end stations send information using cells or packets placed in available slots that are then extracted from those slots by the recipient end station. Each end station can include transmission and receiving units for sending and receiving cells on the ATM network. Generally, end stations can be personal computers, computer work stations, or other computer systems that use adapter cards to provide an interface between a native bus on the end station and the ATM network, or otherwise implement adapter functions. End stations can also be devices or systems that provide interworking adapter functions between ATM and other networking technologies such as ATM end stations that bridge to other networks. The adapter functions performed by end stations often establish and manage numerous virtual channels (VC's) that are identified by virtual channel identifiers (VCI's) in order to structure the transmission of cells or packets.
When transmitting cells or packets on an ATM network, a transmission unit of an adapter card or other adapter element can use a scheduler in order to schedule when cells corresponding to the active virtual channels should be sent. The scheduler thereby provides the transmission unit, for example, with information about which cells to retrieve from end station memory for packaging and transmission across the ATM network. Conventional schedulers generally use a fixed and statically-loaded scheduler table to schedule cells for a fixed number of virtual channels. These conventional schedulers advance a single pointer in sequence through the scheduler table in order to determine, for example, which cell for which virtual channel should be packaged and sent.